Biphasic ATRP

Kubisa et al. [64] have been exploring the use of chiral ionic liquids in polymer synthesis. Using ionic liquids with a chiral substituent on the imidazolium ring for the ATRP of methyl acrylate gave a small but definite effect on polymer tacticity, with more isotactic polymer formed than in simple [BMIM][PF6]. They also found that the use of ionic liquids led to fewer side reactions. Ionic liquids have been used as solvents in biphasic ATRP to facilitate the separation of the products from the catalysts [65]. 

Biphasic ATRP procedures have been the subject of a recent review paper. ... 

Related work was done with variously substituted acrylates in an ionic liquid 87). It was found that the solubility of both monomers and polymers depends on the chain length of the alkyl group linked to the ester. Methyl acrylate and its polymer are soluble in [BMIMJPF. However, butyl acrylate (BA) is only partially soluble, and the corresponding polymer is insoluble in the ionic liquid. The ATRP of BA in the ionic liquid proceeded under biphasic conditions with the catalyst, CuBr/pentamethyldiethylenetriamine, dissolved in the ionic liquid phase. Relatively low-molecular-weight polymer was formed. In this case, as the polymer was insoluble in the ionic liquid, it was spontaneously separated from the ionic liquid phase free of copper contamination. Furthermore, an undesirable side-reaction was significantly reduced in the ionic-liquid-phase ATRP 87). 

Gnanou s group has extensively explored the use of ROMP in emulsion and miniemulsion in addition to dispersion and suspension. The use of ROMP in tandem with ATRP in miniemulsion has proven to be an effective route for making biphasic or Janus particles, consisting of polynorbornene and poly(methyl methacrylate) domains. They were able to use the same ruthenium-based catalyst for both, achieving simultaneous ROMP of norbornene and ATRP of MMA, using miniemulsion polymerization. Stable latexes with minimal... 

Water is a safe, inexpensive and environmentally benign solvent that has been broadly used in industrial scale processes for conventional solution RP of hydrophilic monomers and for biphasic heterogeneous-mediated polymerizations of hydrophobic monomers (oil-in-water) and hydrophilic monomers (water-in-oil). Therefore it was highly desirable to develop conditions that allowed conducting ATRP in aqueous media [95-100]. 

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